The present invention relates to a method for erecting an emergency mast for a power line comprising mast elements placed one on top of another.
Emergency masts for power lines are used after one or more of the original masts have been destroyed by for instance a natural disaster such as an earthquake or tornado, another type of disaster or by sabotage. Emergency power masts can also be deployed to replace a faulty underground cable connection or as temporary connection to replace a cable or above-ground power line which is to be repositioned. There is therefore a need for a mast which can be erected quickly in such emergency situations. This mast can be used per se when only a single mast has been damaged by the disaster, or a series of masts can be used when a significant part of such a power line has been destroyed. Known from the prior art, for instance the KEMA brochure and ELECTRON "Emergency lines . . . , you may need them sooner than you think" is an emergency power pylon which is assembled lying on the ground and subsequently erected by means of a crane, by means of a pivoting hoisting boom or using a helicopter. It is also known to assemble a mast in the erected situation by mounting each of the subsequent elements on top of the already existing mast part using a boom suspended in cables.
All these known methods have drawbacks.
Assembly on the ground thus requires extensive lifting equipment which is usually difficult to take to the intended location and which requires much manpower. It is noted here that such emergency power pylons must usually be erected at locations which are difficult to reach and which are often not flat, so chat the available space is small and assembly and erection in this manner involve difficulties.
It is of course simpler to construct the mast elements by stacking, although this is dangerous because operations take place increasingly higher in the mast, wherein the mast elements must moreover be hoisted upward. This also requires the necessary lifting equipment and in particular the professional skill. In addition, the method is time-consuming because the guys must be constantly displaced.
GB-A 1 409 888 discloses a method for erecting a mast comprising mast elements placed one on top of another, comprising the following steps of:
arranging a lifting device at the location where the emergency mast has to be placed; PA1 arranging a first mast element close by the lifting device; PA1 raising the first mast element by means of the lifting device to a height such that a following mast element can be placed under the first mast element; PA1 placing a following mast element under the first mast element and connecting the following mast element to the mast element situated thereabove; PA1 raising the thus obtained combination by means of the lifting device to a height such that a following element can be placed under the combination; PA1 the lifting device is located next to the location where the mast is to be erected; PA1 the lifting device comprises at least one mast element from which at least two lifting frames extend, and PA1 after the mast has reached the required height, the lifting device is removed.
repeating the latter two steps until the mast has reached the required height.
This known prior art relates to a temporary mast structure for a single radio mast or single signal mast.
The use as a temporary mast in a power line necessitates the use of several and sometimes large numbers of masts. The use of the prior art construction would imply the use of a separate lifting device for each of the masts. This is undesirable for logistic reasons.